Delegates are regular wallets which have registered themselves eligible to become a Delegate by a registration transaction. If a Delegate is amongst the top 51 highest voted (by staked ARK), it may run a forging Node, which produces a block once every 6.8 minutes, awarding the Delegate two ARK + the transaction fees.

Genesis Delegates are the initial, virtualized Delegates. They were not registered nor voted in, and in the Ark mainnet have been replaced by actual Delegates a long time ago.

You can query for a specific delegate by username, address, and public key; thus the following queries will result in an identical response. Note that public keys are always known for delegates, as they have previously transmitted a registration transaction. This is not the case for regular wallets.